EFF: Warrant should be required to obtain cell location data

The Electronic Frontier Foundation, the Center for Democracy and Technology, …

The government shouldn't be able to obtain a person's cell location data without an appropriate warrant, argue the Electronic Frontier Foundation, the Center for Democracy and Technology, the American Civil Liberties Union, and the ACLU of Pennsylvania. The groups have submitted an amicus brief to a federal court in Pennsylvania in response to an application by the government to obtain stored cell site location information (CSLI) from a cell provider, arguing that such records are protected by the Fourth Amendment.

Let's back up a couple of steps. Many mobile users fail to realize their current locations (or nearest approximations thereof) can easily be tracked by their cell providers. There are a couple of levels to which users' locations can be tracked. The first is that it can be triangulated realtime, which many carriers use for e911 services in order to tell emergency personnel how to find a caller. It's also the kind of data that some phones (like Apple's original iPhone and numerous BlackBerrys) running recent versions of Google Maps use in order to pinpoint the user's location without GPS. This data isn't usually stored anywhere and is pulled up on the fly upon request.

The second method is used by some hardware vendors and carriers: they can store a list of specific cell sites that your phone has used recently, which is often used for troubleshooting purposes (a customer might call in and say that a call got dropped an hour ago, and engineers can look to see which site the phone was on in order to identify the source of the problem). This "tracking" method is much less accurate than triangulation, as you could be anywhere within a certain range of a cell tower in order to be using it, but it's still a decent indicator of the general area you were in at a certain time of day. More important, this data is stored for a certain period of time, depending on the hardware used. We believe that this is the issue being argued by the EFF, CDT, and ACLU in this case.

I'm in the circle
What could I be doing here?
Oh, the mystery

In the brief, the groups say that US Magistrate Judge Lisa Lenihan acted correctly when she denied the government's request for a court order to obtain CSLI from a particular cell provider in February. The EFF, CDT, and ACLU say that users' CSLI constitutes data that is protected against government access by the Stored Communications Act portion of the Electronic Communications Privacy Act, which typically requires at least a court order (a "D order") before seizing it.

The groups went on to cite the government's past use of CSLI to identify locations used by targets in a drug conspiracy case as evidence that law enforcement can and will use the data to track the movements of users even when they're not in public. "Without a doubt, the government plans to use CSLI to learn whether suspects are in private places outside of public view," reads the brief. "The government quibbles with Magistrate Judge Lenihan's factual findings but does not promise that it does not and will not use the stored CSLI as evidence that calls are made from a constitutionally protected space or to infer facts about the interiors of private homes."

The groups also argue that CSLI is protected under the Fourth Amendment of the US Constitution, therefore requiring the government to obtain a warrant before demanding such information. They also assert that the plain language reading of the SCA should raise the floor and require the government to obtain a warrant before obtaining CSLI as well.